NPSM Loose CNC Machined Aluminum Cap - Non-Vented

Precision CNC-machined from 6061 aluminum, this 2" NPSM cap is designed for reliable sealing and easy fitment across real-world tank applications. The “loose” NPSM thread tolerance allows for weld distortion and seasonal expansion, making installation smoother while maintaining a secure seal.

This cap includes an FKM (Viton®) gasket for excellent chemical resistance and a stainless-steel lanyard with an 8" aluminum crossbar to prevent loss during servicing.

Features

CNC-machined 6061 aluminum construction

2" NPSM straight threads, 11.5 TPI (loose tolerance)

Compensates for weld distortion and thermal expansion

Non-Vented

Chemical-resistant FKM (Viton®) gasket

Stainless-steel lanyard with 8" aluminum crossbar

Fitment

Fits all Boyd 2" NPSM necks in aluminum, steel, or stainless steel

Thread Type Explained

NPSM (National Pipe Straight Mechanical) threads seal using a gasket, not thread taper. The “loose” fit means threads are machined on the higher end of tolerance to ensure consistent fit and sealing in welded tank necks.